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Biomedical subjects

N Simonetti

Publications and source records attributed to N Simonetti.

At least 37 records · Page 2Linked to original sources
PubMed1994

The lipopeptide antimycotic, cilofungin modulates the incorporation of glucan-associated proteins into the cell wall of Candida albicans.

The effect of the beta 1-3 glucan synthase inhibitor, cilofungin, on the incorporation of 35S-methionine-labelled glucan associated proteins (GAP) in the cell wall of Candida albicans was investigated in a susceptible strain C. albicans 3153 and resistant strain C. albicans CA-2. Cilofungin exerted a marked effect on the GAP composition of the cell wall at 0.25 mg/L, a concentration which reduced beta 1-3 glucan synthesis by approximately 50% and also inhibited the growth of the susceptible strain C. albicans 3153. A 46 kDa protein was present in large amounts in C. albicans 3153 but not in strain CA-2. This protein was probably not mannosylated and its incorporation was greatly reduced by cilofungin. In addition, a well defined 34 kDa protein was identified together with a distinct band of high molecular mass polydisperse material of between 65 and 96 kDa and another of > 200 kDa. These proteins were strongly reactive to concanavalin A indicating that they were mannosylated, and treatment with cilofungin caused an increase in their production which was also confirmed by immunoblotting with rabbit anti-Candida serum. In contrast, exposure of the drug-resistant strain CA-2 to cilofungin did not result in changes in the composition of the GAP constituents. Only the mannosylated proteins of 34 kDa and the high molecular mass polydisperse material 65-96 kDa were present in the cell wall. The pulse-chase labelling experiments showed that the 46 kDa protein was the first of the GAPs to be incorporated into the cell wall, and that this was suppressed in the presence of cilofungin whereas there was a concomitant increase in the incorporation of the 34 kDa and the high-molecular weight polydisperse material. Thus, cilofungin causes a profound imbalance in GAP incorporation into the growing cell wall which is possibly related to changes in the amount and type of glucan being synthesized at sub-inhibitory concentrations of the antimycotic.

Antifungal Agents↗
PubMed1993

Antifungal agents, II: Synthesis and antifungal activities of aryl-1H-pyrrol-2-yl-1H-imidazol-1-yl-methane derivatives with unsaturated chains.

The synthesis and antifungal activities of aryl-1H-pyrrol-2-yl-1H-imidazol-1-yl-methanes having allyl, crotyl, and acrylate chains linked to the N-pyrrole atom and substituted at phenyl ring by Cl, F, CH3, and NO2 groups are reported. In vitro tests against Candida albicans and Candida spp. showed 2,4-dichlorophenyl-1-allyl-1H-pyrrol-2-yl-1H-imidazol-1-yl-methane to be the most potent derivative with activities comparable to those of ketoconazole and slightly inferior to those of bifonazole and miconazole. Some structure-activity relationships are discussed.

Antifungal Agents↗
PubMed1993

Variations in the antigenic effects of tunicamycin on Candida albicans.

We report on the effect of subinhibitory doses of tunicamycin on Candida albicans cells (BP strain high responder NCYC 1466) in a defined medium favourable for expression of the mycelial phase. Tunicamycin inhibited the synthesis of some protein fractions ranging from 40 to 65 kDa, where the immunodominant antigens of C. albicans responsible for the antibody response to systemic mycosis were inhibited. By two-dimensional immunoelectrophoresis, antigen extracts from the cell cultures grown with tunicamycin showed a migration modification and a lower number of precipitation arcs with variation in their height and range.

Antigens, Fungal↗
PubMed1993

Antifungal agents. VI. In vitro antifungal activities of halobenzoyl esters of cis- and trans-[2-(1,1'-biphenyl-4-yl)-2-(1H-imidazol-1-ylmethyl)-1,3- dioxolan-4-yl]carbinols.

The synthesis and the in vitro antifungal activities against Candida albicans and Candida spp of a number of halobenzoyl esters of cis- and trans- [2-(1,1'-biphenyl-4-yl)-2-(1H-imidazol-1-ylmethyl)-1,3-dioxolan -4- yl]carbinols is reported. Some new imidazoles were found more active than ketoconazole and sometimes as potent as bifonazole against Candida albicans. All derivatives were found scarcely active against Candida spp.

Antifungal Agents↗
PubMed1992

Glucan synthesis and its inhibition by cilofungin in susceptible and resistant strains of Candida albicans.

The lipopeptide antimycotic agent, cilofungin, at a dose of 20 micrograms ml-1, inhibited beta 1-3 glucan synthesis in a drug-susceptible strain (3153; minimum inhibitory concentration (MIC) < 1 microgram ml-1) as well as in a drug-resistant strain of Candida albicans (CA-2, derived from 3153 by nitrosoguanidine mutagenesis; MIC > 50 micrograms ml-1). This was demonstrated for both whole cells under growing and non-growing conditions, and during protoplast regeneration. However, time-effect experiments, during growth of a CA-2 culture initially exposed to an inhibitory dose of cilofungin, showed that this strain was able to progressively regain both glucan synthesis and a growth rate comparable to that of cultures that had not been treated with the drug. This recovery was not attributable to cilofungin instability or degradation within the CA-2 culture. Our study suggests the existence of an as yet unknown drug-related and/or cell-related factor(s) modulating the inhibition of glucan synthesis, and then contributing to the actual inhibitory effects of cilofungin in C. albicans.

Antifungal Agents↗
PubMed1992

Electrochemical Ag+ for preservative use.

In contact experiments with different experimental conditions, electrochemical Ag+ solutions exhibited better antimicrobial effectiveness against bacteria, a yeast species, and a mold than did analogous silver solutions from inorganic salts. The particular characteristics of electrochemical Ag+, such as the mode of action, effectiveness at low concentrations, and stability, indicate that Ag+ could be used effectively in preservatives.

Anti-Bacterial Agents↗
PubMed1991

Antimicrobial contact activity of econazole sulfosalicylate.

The aim of this investigation was to compare the contact action of econazole sulfosalicylate (E-SSA) on mycetes (Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus, Trichophyton rubrum, T. cutaneum, Pityrosporum sp.), Gram-positive bacteria (Staphylococcus aureus, Streptococcus faecalis) and Gram-negative bacteria (Escherichia coli, Citrobacter freundii) with that exerted by econazole nitrate (E-NIT). The results show E-SSA activity greater than E-NIT (in particular against mycetes and Gram-negative bacteria). The E-SSA contact activity trials illustrated certain properties of this imidazole sulfosolicylate such as: absence of latency time, antimicrobial activity proportional to its concentration, when a high concentration is used, given the limiting influence of pH and ionic strength of the medium. The higher E-SSA contact activity, in relation to E-NIT, can be correlated to its greater lipophylia considering also the lipophylic properties of SSA and the scarce dissociation of E-SSA.

Aspergillus fumigatus↗
PubMed1991

Increased in vitro sensitivity of Candida albicans to fluconazole.

Sodium dioctyl sulfosuccinate (SDSS), an anionic surfactant used at a non-antimicrobial concentration, increased the sensitivity of Candida albicans to fluconazole in complex media (such as Sabouraud). The conditions were assessed to determine the in vitro sensitivity to fluconazole. In this connection, the use of a liquid medium at a non-alkaline pH is important. The presence of SDSS in complex media does not seem to affect the neutralization of a particular substances but favours the activity of fluconazole.

Candida albicans↗
PubMed1990

Researches on antibacterial and antifungal agents, XII: Analogues of bifonazole with two imidazole moieties and related azoles.

Analogues of bifonazole bearing two imidazole rings and other related azoles have been synthesized and tested as antifungal agents against Candida albicans and Candida spp.. Only a slight part of the antifungal power of the parent drug is retained by some derivatives as evinced by the comparison of new compounds with bifonazole, miconazole, and ketoconazole.

Antifungal Agents↗
PubMed1990

Macrophage lysozyme stimulation by fructose-1-6-diphosphate.

FDP produces an increase of serum lysozyme concentration which may be related to stimulation of the phagocytic activity. Mice macrophages in vitro produce extracellular and intracellular LSZ (lysozyme) and FDP (fructose-1-6-diphosphate) increases this production. Also in vivo FDP stimulates the macrophages intracellular lysozyme production. The toxic activity in vitro and the protection in vivo against Staphylococcus pyogenes after FDP administration can also be related to macrophage stimulation.

Animals↗
PubMed1990

Investigations of the activity by contact of miconazole sulfosalicylate.

The in-vitro antimicrobial activity of miconazole sulfosalicylate (M.SSA) has been investigated on mycetes (Candida albicans, Cryptococcus neoformans, Aspergillus niger, Trichophyton mentagrophytes), Gram-positive bacteria (Staphylococcus aureus, Streptococcus faecalis) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens and Proteus vulgaris) in comparison with miconazole nitrate (M.NIT). The results showed M.SSA has a greater activity than M.NIT, particularly on mycetes and Gram-negative bacteria. The study of activity by contact with M.SSA showed some characteristics of this sulfosalicylate imidazole, such as the lack of a latency time, an antimicrobic action related directly to the concentration, the limited influence of pH and ionic strength of medium used. The greater activity by contact of M.SSA than M.NIT could be related to its higher lipophilia (due also to the lipophilic characteristics of SSA) and, therefore, to increased interaction with the cell membrane.

Candida albicans↗
PubMed1990

In vitro antimicrobial activity of econazole and miconazole sulfosalicylate.

The in vitro activities of new sulfosalicylic salts of econazole (E.SSA) and miconazole (M.SSA) have been investigated in comparison with the respective nitrate (NIT) salts and sulfosalicylic acid (SSA) alone. The results reveal good antimicrobial activity of M.SSA and E.SSA against different strains of Candida, dermatophytes, moulds, Gram-positive bacteria and Trichomonas vaginalis. The MIC values demonstrate that M.SSA is more active than M.NIT on Candida and T. vaginalis. E.SSA was also more active than E.NIT on T.vaginalis. Both SSA and sodium sulfosalicylate (NaSSA) were practically without activity by themselves. Finally, the pH variations did not significantly modify the activity of the SSA salts, suggesting that their greater activity could be due to better lipophilic activity of these compounds with respect to the nitrate salts.

Animals↗
PubMed1989

Researches on antibacterial and antifungal agents, X. Synthesis and antifungal activities of 1-(p-methyl-alpha-[4-(1H-pyrrol-1-yl)phenyl]benzyl)azoles and some related products.

The synthesis and antifungal activities against Candida albicans and Candida spp. of some pyrrole analogues of bifonazole are reported. 1-(p-Methyl-alpha-[4-(1H-pyrrol-1-yl)phenyl]benzyl)imidazole was found to be equipotent or sometimes superior to bifonazole and ketoconazole, and lightly inferior to miconazole. Substitution of the imidazole moiety with other azoles retained some activities. No activity was shown when the azole aromatic rings were replaced by the heteroalicyclic ones.

Antifungal Agents↗
PubMed1989

Action of the ketoconazole-alkylaminoethylglycine combination on Candida albicans.

High concentrations of ketoconazole (Ktc) exhibit poor antimicrobial activity in microbicidal test. Alkylaminoethylglycine (AAEG), an amphoteric surface-active agent, employed in subinhibitory concentrations, can enhance the action of ketoconazole. The Ktc-AAEG combination causes a higher rate of potassium ion release compared to both drugs separately. The increased ketoconazole activity may be ascribed to the membrane damage indicated by increased permeability to potassium ions.

Candida albicans↗
PubMed1989

Research on antibacterial and antifungal agents. XI. New antibacterial quinolones related to pirfloxacin.

The synthesis and antimicrobial activities against Gram-positive and Gram-negative bacteria of some 1-substituted quinolones related to pirfloxacin are reported. Compounds with a benzyl moiety at 1-position were generally found to be less active than the analogues bearing an unsaturated alkyl chain at the same position. Introduction of fluorine or chlorine in the benzyl moiety did not increase the antibacterial activity. All derivatives here reported were inferior to pirfloxacin as regards antibacterial power, but always superior in comparison with nalidixic acid and pipemidic acid against Gram-positive microorganisms.

Anti-Infective Agents↗